MEXICO CITY — After several days of closed-door meetings and interrogations, Swiss and Mexican authorities confirmed here Wednesday that the elder brother of former President Carlos Salinas de Gortari amassed at least $100 million in suspected drug money and is the target of an international money-laundering investigation.

Switzerland's top federal prosecutor, Carla del Ponte, on an official visit to Mexico to oversee the probe, said in a written statement that she and her top counter-narcotics agents positively linked a series of Swiss bank accounts to Raul Salinas de Gortari after sitting in on interrogations of him at a prison near Mexico City, where he is being held on murder charges.

The Swiss government, she said, launched the investigation after the U.S. Drug Enforcement Administration supplied information that led Swiss agents to the accounts in Geneva, where they arrested Raul Salinas' wife and her brother on Nov. 15 as the pair attempted to withdraw more than $83 million.

Mexico's attorney general, Antonio Lozano, confirmed to the nation's Congress on Wednesday that those and other accounts now frozen by the Swiss government contain more than $100 million. Authorities earlier reported that Raul Salinas used a fake name to open the accounts.

"In the investigations, it was discovered that the beneficial owner is Mr. Raul Salinas de Gortari," Del Ponte's statement said. "For that reason, Swiss and Mexican authorities are jointly investigating these facts. Due to the secrecy of the proceedings, Swiss authorities cannot reveal more information on the case at this time."

U.S. and Mexican investigators privately have told The Times that Raul Salinas' accounts in Switzerland and elsewhere in Europe may well exceed $250 million. They said they are investigating whether the money was from Mexico's powerful drug cartels, which supply the U.S. with billions of dollars in cocaine each year.

Mexican prosecutors said Raul Salinas also is under investigation for possible embezzlement or extortion, after they disclosed that he moved millions of dollars through more than 40 bank accounts during the decade he served in public office.

The elder Salinas, who is on trial for allegedly masterminding last year's murder of the ruling Institutional Revolutionary Party's second-ranking official, has asserted that the money is from legal sources, which he said he will prove.

After observing Salinas' interrogation by Mexican federal prosecutors, Del Ponte stated Wednesday that the large sums her agents found in those accounts "are suspected to be from the laundering of money related to narcotics trafficking."

Members of the Swiss delegation, which includes that nation's anti-narcotics chief, Valentin Roschacher, began arriving in Mexico City on Sunday to attend the interrogations, share intelligence and develop investigative strategies with their Mexican counterparts. Before her formal statement Wednesday, Del Ponte's investigators had said only that the arrests of Raul Salinas' wife, Paulina Castanon, and her brother Antonio were part of an international money-laundering probe.

Such candor is rare for the Swiss. The traditionally secretive banking system is a cornerstone of their nation's economy, and they have opened those accounts only on rare occasions. U.S. and Mexican law-enforcement analysts said Del Ponte's relative openness in the Raul Salinas case is a clear indication that Swiss authorities want to crack down on the use of their banks to launder the proceeds of the multibillion-dollar-a-year international narcotics trade.

Mexico's President Ernesto Zedillo has declared war on drug-money laundering, a practice in which the international trafficking cartels use bank accounts in countries with banking-secrecy laws to turn illegal profits into legal assets. Zedillo introduced a law in the Mexican Senate last week classifying money laundering as a felony punishable by 500 to 5,000 days in prison.

The U.S. Treasury Department's undersecretary for enforcement, Ronald Noble, has estimated the dimension of the problem: Each year, he said, up to $300 billion in illicit profits are laundered by criminal syndicates worldwide.

And last week, Treasury Secretary Robert E. Rubin said, "There are estimates that $100 billion in drug money alone moves through the U.S. economy."